There is an image processing apparatus for estimating, from image data, the amount of a pigment component accumulated in human skin. In this image processing apparatus, the image capturing environment at the time of capturing image data needs to be known in order to estimate a pigment component amount.
Against this backdrop, there has arisen a demand for an image processing apparatus capable of estimating the amount of a pigment component accumulated in human skin from image data captured under a general environment where the image capturing environment is unknown.